Chemical polarization of nuclei. Proton polarization during thermal decomposition reaction of dimethyl perdiglutarate

Proton chemical polarization was observed in methyl butyrate, γ-butyrolactone and in some other products of the dimethyl perdiglutarate decomposition reaction. The polarization pattern of the α-CH₂ and β-CH₂ groups in butyrolactone is just as one would expect in the products of the CH₃OCH₂CH₂?H₂ radical which has left the pair of identical radicals. Thus butyrolactone is formed from the CH₃OCH₂CH₂?H₂ radical by means of intramolecular cyclization and elimination of the methyl radical.